Spinning band distillation column and modular automation

The investigated spinning band distillation column (SBDC) is built as a modular process equipment assembly according to VDI 2776. It consists of a DN25 glass column with a solid rotating internal - the spinning band (Figure 1 right) manufactured by Normag-Pfaudler, Ilmenau, Germany. Hence there is only a thin gap for the countercurrent liquid-vapor flow between the spinning band and the wetted glass wall of the column. The rotation induces an intensified mass transport between liquid and vapor, resulting in better separation efficiency with higher rotation speed. On the other hand, increasing the band speed, pressure drop is increasing due to higher liquid loading and higher vapor velocities in the column. At a certain point, depending on band speed, liquid loads, and vapor velocity, the liquid is accumulating which results in flooding. Flooding can be seen visually but also by very steep rise of the pressure drop sensor, which is measuring the pressure difference between bottom and head of the distillation column.